dt-bindings: rng: Northstar Plus SoC rng bindings

Document the bindings used by Northstar Plus(NSP) SoC random number
generator.
Signed-off-by: NYendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>
Acked-by: NEric Anholt <eric@anholt.net>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Documentation/devicetree/bindings/rng/brcm,bcm2835.txt

@@ -2,7 +2,7 @@ BCM2835 Random number generator
 
 Required properties:
 
-- compatible : should be "brcm,bcm2835-rng"
+- compatible : should be "brcm,bcm2835-rng"  or "brcm,bcm-nsp-rng"
 - reg : Specifies base physical address and size of the registers.
 
 Example:
@@ -11,3 +11,8 @@ rng {
         compatible = "brcm,bcm2835-rng";
         reg = <0x7e104000 0x10>;
 };
+
+rng@18033000 {
+	compatible = "brcm,bcm-nsp-rng";
+	reg = <0x18033000 0x14>;
+};